It has been attempted to develop TGF-β super family molecule itself, or antagonist or agonist thereof as a pharmaceutical based on focusing the function of TGF-β super family, and some pharmaceutical screening methods therefor have been proposed.
For example, (1) as a method for screening by using cell system, there are screening methods for agonist or antagonist by using the activity of TGF-β super family in growing, differentiating, killing or maintaining animal cells as an indicator. Those methods are, for example, (i) a screening method using inhibition activity of TGF-β on the growth of a tumor cell, or propagation accelerating activity of it on the growth of another tumor cell as an indicator, (ii) a screening method focusing on the immuno suppression activity of TGF-β, and (iii) a screening method focusing on production accelerating effect on extracellular matrix by TGF-β. Furthermore, (2) a screening method focusing on the interaction between TGF-β super family and TGF-β receptor super family is known.
However, it is known that TGF-β super family has significantly wide-ranging functions, and thus, a mere agonist or antagonist for TGF-β super family may have a problem such that main function and side function can not be sufficiently differentiated, and consequently they are not sufficient for a screening method for pharmaceuticals. That is, the above screening method can not differentiate only main function from other functions, and very likely screen materials with low specificity not to be an candidate for pharmaceuticals. Furthermore, even if a useful candidate for pharmaceuticals could be screened, it still remains dificulty to find guideline for synthesizing a useful derivatives and to do molecular designing.